Compact reversible universal mill for producing medium-large sections

ABSTRACT

A compact reversible universal mill for producing medium-large sections has a universal reducing stand, a two-high stand and a universal stand to create a reversible intermediate unit across a roller way carrying a bar being worked. Provided immediately downstream of the reversible intermediate unit is a finishing stand being the final additional stand and extending also across the shared roller way or respectively moveable perpendicularly in relation to the roller way. The finishing stand is kept open or respectively closed during intermediate passes of a production cycle and being closed or respectively used on the roller way only before the bar completes the final pass of the production cycle.

This invention relates to a compact reversible universal mill forproducing medium-large sections.

In the last ten years, economic development and research have increasedthe use of ever-more innovative civil engineering solutions makingextensive use of sections to improve versatility, lightness andelasticity, and they have caused steel manufacturers to turn to themarket for solutions to produce such sections. Indeed, the use of light,elastic structures is becoming an essential requirement for constructingtall buildings and increasingly extreme architectural solutions.

Population growth in areas that are already densely populated isresulting in the construction of increasingly tall skyscrapers thatrequire structures that are both elastic and rigid.

In this context, therefore, market demand for medium-large sections hasincreased considerably, and as a result large industrial groups areviewing the section market as increasingly profitable, and consequentlyreviewing their investments in plants capable of producing this type ofproduct.

In consideration of this demand, plant manufacturers are leaning towardsengineering plants to produce medium-large sections (girders, IPE, IPN,HE, sheet piling, angle, etc.) There are essentially three plant andtechnology solutions currently available:

1. Continuous section rolling mill.

2. Semi-continuous section rolling mill.

3. Reversible section rolling mill.

The reversible mill in the third solution provides various advantagesover the continuous mill in the first two, but the main factor isessentially the lower initial investment cost. Indeed, reversiblerolling mills reduce the number of machines required for rolling, enablesmaller hangars and related structural work to be used, provide processand productivity advantages, etc. Consequently, reversible mills aregenerally the preferred type.

Patent EP 256 409 B1 from SMS describes a process for producing suchsections using a reversible mill known as “X-H”.

The X-H process solution adopted by SMS to produce sections provides forone or more reversible breakdown stands and an intermediatereversible-finishing mill (tandem) comprising a universal reducingstand, a two-high stand and a universal stand that fulfills the dualfunctions of reducing and finishing.

This reduces the number of stands required in the reversible mill. Thissolution does however present disadvantages.

The most significant is the need to use the last stand in the finishingmill as a reducing and finishing stand. This obviously createssignificant wear issues in the rolls that, subjected to considerableloads to reduce the material in the intermediate passes, generates suchwear as to require the rolls to be changed frequently in order to keepwithin the desired dimensional tolerances.

An alternative solution for producing sections using a differentreversible mill is also used. This solution provides for the use of oneor more breakdown stands, an intermediate reversible mill comprisingU-H-U (like the competition) and a continuous finishing mill comprisinga horizontal stand (optional—providing the function of an edger) and auniversal stand.

An additional stand is provided away from the intermediate reversiblemill and therefore linked by roller way and located as a finishing standnear to the cooling bed.

In this solution the last stand in the finishing mill has a durationthat is 2-3 times higher than the solution in the aforementioned SMSpatent generating significantly fewer stops in production to replacerolls and therefore considerably less maintenance.

In this last alternative solution to the SMS patent with an additionalfinishing stand the last stand is not used for intermediate passes. Thisadditional stand is subjected to considerably less load and thereforeless wear enabling many more tons to be rolled without jeopardizing thequality of the finished product.

This option uses the additional stand, unlike the aforementioned patent.Furthermore, this arrangement requires the addition of specificequipment for producing sections.

Indeed, the finishing stand, the roller way and all of the structuralwork and hangars related to the longer plant increase the overallinvestment by the client.

The general purpose of this invention is to resolve the aforementioneddrawbacks in the prior art in an extremely simple, economical andparticularly functional manner. Another purpose is to provide areversible mill that is more compact than those currently available.

Another purpose is to provide a reversible mill that minimizes plantcosts related to the structural work and hangars required.

In consideration of the aforementioned objectives, this inventiondescribes a compact reversible universal mill for producing medium-largesections, having the characteristics set out in the attached claims.

The structural and functional features of this invention and itsadvantages compared to the prior art will become even more evident byexamining the description below, which refers to the drawings attached,which illustrate an embodiment of a compact reversible universal millfor producing medium-large sections according to this invention.

In the drawings:

FIG. 1 shows the key elements of a compact reversible universal mill forproducing medium-large sections according to this invention;

FIG. 2 shows a first embodiment of a plant, known as “I shape”, whichincorporates a mill according to the invention;

FIG. 3 shows a second embodiment of a plant, known as “U shape”, whichincorporates a mill according to the invention;

FIG. 4 shows a third embodiment of a mixed-type plant, which alsoincorporates a mill according to the invention. With reference primarilyto FIG. 1, a compact reversible universal mill for producingmedium-large sections is indicated as a whole by 10.

As shown, according to this invention, the reversible universal mill 10provides for the placement of a finishing universal stand 11 as thefinal additional stand in a reversible intermediate unit 12 across aroller way 13 carrying a bar 17 being worked.

The reversible intermediate unit 12 includes a first universal reducingstand 14, a two-high stand 15 and a second reducing universal stand 16.

The function of this additional stand 11 does not change as it is usedalways and exclusively for finishing. Therefore the stand 11 is alwaysopen during intermediate passes and is only closed before the barcompletes the last pass in the production cycle.

In an alternative solution, of which only the arrow F appears in FIG. 1,the stand 11 is kept closed in a standby position away from the rollerway 13 and is inserted only before the final pass of the bar 17.

The stand 11 therefore moves perpendicularly to the direction ofmovement of the bars 17 gradually worked by the stand 11 itself. Thismovement is for example effected by an appropriate actuating unit, shownin 18, possibly connecting to and disconnecting from the actuatorsbelonging to the stand 11.

This ensures that the groove time values remain unchanged, providing theproduction advantages set out above.

This arrangement consists of an X-X-H solution using a reversible millcomprising four full stands substantially limiting the distance betweenthe finishing stand 11 and the reversible intermediate unit 12.

Indeed, this finishing stand 11 is no longer placed away from thereversible intermediate unit 12, as described in the prior art, but isplaced immediately after the last universal stand of the same reversibleunit 12.

This results in a total plant length that is less than the solution usedto date, and therefore less mechanical equipment and a smaller totalhangar area to cover the mill with obvious savings for the client interms of plants, whether turnkey or not.

The presence of an additional finishing stand also improves the qualityof the final product as well as improving process flexibility.

Furthermore, the option of offering clients ever-more compact plants,such as those according to this invention, enables involvement incontracts where the installation area is not critical, as well asinvolvement in contracts where the actual layout is critical to millinstallation.

Increased production offsets the higher initial cost of the plantaccording to the invention compared to known plants in less than oneyear's operation of the plant, depending on the capacity of the plantand the tons per campaign. The service life of the rolls of theuniversal finishing stand according to this invention is around 2000 [t]for smaller sections and around 3000 [t] for larger ones.

This could mean that for smaller campaigns with our solution the plantneed never stop to change grooves, compared to one or two stops tochange rolls in the finishing stand in the prior art. Similar benefitsmay be gained for larger campaigns reducing stops to a maximum of one tochange the rolls of the finishing stand.

This ensures that the groove time values remain unchanged, providing theproduction advantages set out above. The solution proposed can bereferred to as “XXH”.

The advantages of the XXH solution compared to the existing solution arethe smaller total footprint of the plant and the option of producing twoplate bars per bloom produced optimizing furnace loads.

With the XXH solution the structural part of the plants are considerablycheaper.

From an operational perspective, the arrangement proposed makes theplant more compact or in any case significantly optimizes the process.The solution proposed generates a single-change system for the stands ofthe reversible mill and therefore a more compact rollshop section, areduced and optimized use of overhead cranes, more rational use of spareparts and therefore better warehouse management. This naturally resultsin fewer maintenance staff and shorter mill change times (the 4 nearbystands enable just one operator to be present).

Furthermore, warehouse management and stand movement, facilitated by therational use of spare stands, also enables the rollshop to be remotelylocated in different locations without compromising its operation andtherefore mill productivity.

The “I Shape” solution shown in FIG. 2 results in a more compact layoutand enables the roller ways, lubricant, hydraulic, air, water and greasepipes to be shorter, reducing the impact on the operation andmaintenance part.

In this embodiment of the plant a furnace unit 21 with relatedaccessories (such as descaler 23) is placed upstream before a roughingunit 24. This is followed by the mill 10 according to the inventionbefore a cooling bed 27, cutting stations 29 and final stations.

Very similarly, except for the arrangement, the “U shape” solution shownin FIG. 3 with bed 27 further away (due to and necessary for thearrangement of the stacking, binding and sorting equipment for thefinished product) results in any case, once the final stand is moved, ina more compact layout. In any case the compact solution may enable useof the space after the finishing stand to be optimized and the distancebetween it and the cooling bed to be lengthened at a lower cost makingit possible to roll a longer finished product from a starting sectionthat is heavier and to cut it into multiples of the length of the bedbefore the bed using the saw. This naturally improves productivity andyield and plant productivity at a lower investment cost.

FIG. 4 shows a third embodiment of a plant that incorporates the millaccording to this invention and that combines characteristics of the “Ishape” plant with those of the “U shape” plant shown before, mixing andadapting them. In summary, we can speak of the following advantages overthe SMS patent:—advantages on account of the reduction of finishingstand change times which result in fewer plant stoppages and thereforegreater production;—moreover fewer changes reduces the times and costsof preparing the finishing stand in the workshop;—optimizing the servicelife of the finishing groove that in the solution proposed only performsthe finishing function and not the reducing function also makes itpossible to reduce the investment costs for the number of rolls;—thesolution with 4 stands enables greater flexibility in rolling and beingable to use both reducing passes for each sequence enables plantproductivity to be improved;—better tolerances on the finished productsince the finishing stand has a dedicated groove that wears less overtime. And the following advantages compared to the previous unit (3+1)with separate finishing stand, i.e.:—reduction of spaces required toproduce the section;—lower energy consumption as the bar is finishedimmediately after roughing without further temperature losses.

The description above with reference to the figures clearly shows how acompact reversible universal mill for the production of medium-largeprofiles according to the invention is particularly useful andadvantageous. Thus the objective in the preamble to the description isachieved.

Naturally, the forms of the compact reversible universal mill for theproduction of medium-large profiles according to the invention may bedifferent to that shown purely by way of a non-limiting example in thedrawings, and the materials used may also be different.

The scope of protection of the invention is therefore determined by theattached claims.

1-7. (canceled)
 8. A compact reversible universal mill for producingmedium-large sections, the compact reversible universal mill comprising:a roller way for carrying a bar to be worked; a reversible intermediateunit containing at least one first universal reducing stand, a two-highstand and a second reducing universal stand, said reversibleintermediate unit disposed across said roller way carrying the bar to beworked; and a finishing universal stand disposed immediately downstreamof said reversible intermediate unit, said finishing universal standbeing a final additional stand also disposed across said roller way,said finishing universal stand being kept open during intermediatepasses of a production cycle and closed only before the bar completes afinal pass of the production cycle.
 9. A compact reversible universalmill for producing medium-large sections, the compact reversibleuniversal mill comprising: a roller way for carrying a bar to be worked;a reversible intermediate unit containing at least one first universalreducing stand, a two-high stand and a second reducing universal stand,said reversible intermediate unit disposed across said roller waycarrying the bar to be worked; and a finishing universal stand disposedimmediately downstream of said reversible intermediate unit and being afinal additional stand moveable perpendicularly in relation to saidroller way, said finishing universal stand being kept closed away fromsaid roller way during intermediate passes of a production cycle andmoved across said roller way only before the bar completes a final passof the production cycle.
 10. A method for producing medium-largesections in a reversible universal mill, the reversible universal millhaving a reversible intermediate unit with at least one first universalreducing stand, a two-high stand and a second reducing universal standall disposed across a roller way for carrying a bar being worked, thereversible universal mill having immediately downstream of thereversible intermediate unit, a finishing universal stand as a finaladditional stand also across the shared roller way, which comprises thesteps of: keeping the finishing universal stand open during intermediatepasses of a production cycle and a subsequent phase in which thefinishing universal stand is closed only before the bar completes afinal pass of the production cycle.
 11. A method for producingmedium-large sections in a reversible universal mill, the reversibleuniversal mill containing a reversible intermediate unit having at leastone universal reducing stand, a two-high stand and a second reducinguniversal stand all disposed cross a roller way for carrying a bar beingworked, the reversible universal mill having immediately downstream ofthe reversible intermediate unit a finishing universal stand as a finaladditional stand moveable perpendicularly in relation to the roller way,which comprises the steps of: during a given phase, keeping thefinishing universal stand closed away from the roller way duringintermediate passes of a production cycle and a subsequent final phasein which the finishing universal stand is moved across of said rollerway only before the bar completes a final pass of the production cycle.12. A plant for producing medium-large sections, the plant comprising: afurnace unit having related accessories; a roughing unit disposeddownstream of said furnace unit; a cooling bed; cutting stations; finalstations; a compact reversible universal mill disposed between saidroughing unit and said cooling bed, said compact reversible universalmill containing: a roller way for carrying a bar to be worked; areversible intermediate unit containing at least one first universalreducing stand, a two-high stand and a second reducing universal stand,said reversible intermediate unit disposed across said roller waycarrying the bar to be worked; and a finishing universal stand disposedimmediately downstream of said reversible intermediate unit, saidfinishing universal stand being a final additional stand also disposedacross said roller way, said finishing universal stand being kept openduring intermediate passes of a production cycle and closed only beforethe bar completes a final pass of the production cycle.
 13. The plantaccording to claim 12, wherein said cooling bed is disposed immediatelydownstream of said compact reversible universal mill.
 14. The plantaccording to claim 12, wherein said cooling bed is disposed separatefrom and downstream of said compact reversible universal mill.